1. Field of the Invention
The present invention relates to a thin-film magnetic head which performs a magnetic recording action by a perpendicular recording scheme, a method of manufacturing the same, a head gimbal assembly, and a hard disk drive
2. Related Background Art
In recent years, hard disk drives have remarkably been improving their areal recording density. The areal recording density of hard disk drives has recently reached and is about to exceed 160 to 200 GB/platter in particular. In keeping with this trend, thin-film magnetic heads have been required to improve their performances.
The thin-film magnetic heads can roughly be classified according to their recording schemes into those of longitudinal magnetic recording type and those of perpendicular magnetic recording type. The longitudinal magnetic recording scheme records data in a (longitudinal) direction within a recording surface of a hard disk (recording medium), while the perpendicular magnetic recording scheme records data such that the direction of recording magnetization formed in the hard disk is made perpendicular to the recording surface. The thin-film magnetic heads of perpendicular magnetic recording type have been considered more promising than those of longitudinal magnetic recording type, since they can realize a much higher recording density than that in the longitudinal magnetic recording scheme, while their recorded hard disks are less susceptible to heat fluctuation.
Conventional thin-film magnetic heads of perpendicular magnetic recording type are disclosed in U.S. Pat. Nos. 6,504,675 (referred also to as patent document 1), 4,656,546 (referred also to as patent document 2), and 4,672,493 (referred also to as patent document 3) and Japanese Patent Application Laid-Open No. 2004-94997 (referred also to as patent document 4), for example.
Meanwhile, a conventional magnetic head of perpendicular magnetic recording type (perpendicular magnetic recording head which will also be referred to as “PMR” in the following) has a magnetic pole layer and a thin-film coil. The PMR has a structure of electromagnet which the thin-film coil are wound around the magnetic pole layer. As a conventional PMR, PMR 400 as illustrated in FIG. 33 has been known. This PMR 400 includes a main magnetic pole layer 402 which is formed on an insulating layer 401 and has a bevel-shaped magnetic pole end part disposed on the side of an medium-opposing surface (referred also to as air bearing surface, ABS) 403; a write shield layer 405 which is magnetically connected to the main magnetic pole layer 402 and opposes the main magnetic pole layer 402 by way of a recording gap layer 404 on the ABS 403 side; and a thin-film coil 406.
The thin-film coil 406 is wound in a planar spiral about a junction part 408 connecting the main magnetic pole layer 402 and the write shield layer 405, while its windings are insulated from each other by a coil-insulating layer 407. Further, the PMR 400 has a reproducing head 409.